1. Because of the difference in coating treatment, textile density and fabric, plus the difference in testing standards, there are differences between parasols and umbrellas. Generally speaking, a small amount of rain has little effect on the umbrella, but if the number and duration of the rain increase, the sun protection performance will also be reduced.
2. UPF (ultraviolet protection factor) can be used as an important index to evaluate the UV protection function of parasols, but it is not the only index, only when UPF is greater than 40, and T (UVA) AV (refers to UVA, that is, the wavelength of 320 ~ 420nm The average transmittance of ultraviolet rays, the smaller the value, the smaller the transmittance) When it is less than 5%, it can be called "UV protection product".
3. Under the same other conditions, the darker the color of the textile, the lower the UV transmittance and the better the UV protection performance. At this time, the black umbrella is indeed more sun-proof than the white umbrella.
In the hot summer, sun protection is a topic that cannot be avoided. In addition to applying sunscreen, the use of umbrellas is also a choice for many people. What is the difference between a sunshade and an umbrella? Are black umbrellas more sun-proof than white umbrellas? Will the sun protection performance be affected if the umbrella is in the rain?
1. Is there a difference between a sunshade and an umbrella?
True appraisal: There are differences, and there are differences in process, structure and testing indicators.
First of all, the coating treatment of parasols and ordinary umbrellas is different. The main function of the umbrella is wind and rain protection, while the main function of the sun umbrella is sun protection and UV protection. Generally, the umbrella surface coating of the umbrella is mainly a waterproof coating, and the sun umbrella uses a coating with ultraviolet shielding function such as silver glue.
Secondly, the fabric density and fabric are different. The fabric of the sunscreen umbrella is generally tighter than that of the umbrella, which can block ultraviolet rays.
Again, the testing standards are different. The indicators for evaluating the quality of umbrellas include the rainproof performance of the umbrella surface, the color fastness of the umbrella surface to water, the wind resistance of the umbrella shaft and ribs, etc. These indicators can reflect the wind resistance of the umbrella and the rust resistance after exposure to rain; The sunshade also depends on its anti-ultraviolet performance, which is comprehensively evaluated through the detection of ultraviolet protection coefficient and average transmittance.
These differences in technology, structure, and testing indicators constitute the main difference between sunshades and umbrellas.
2. Will the sun protection performance decrease after the umbrella coating surface is exposed to rain?
True appraisal: a small amount of rain has little effect on the sun protection performance of the umbrella coating surface, but with the increase in the number of rains, the number of uses and the length of time, the sun protection performance will indeed decrease.
The sun protection function of parasols on the market is mainly achieved through the UV protection effect of the umbrella cloth itself, or an additional anti-ultraviolet coating on the umbrella cloth. The coating process is generally to uniformly disperse an appropriate amount of ultraviolet shielding agent into the coating liquid, and then coat the coating liquid on the surface of the umbrella leather, and then dry and necessary heat treatment to form a film. The coated umbrella surface can reduce the amount of ultraviolet light transmitted to achieve the purpose of sun protection.
The coating is indeed affected by external factors such as friction and rain. Umbrellas are used to prevent rain. After a long time, the umbrella surface is corroded by acidic substances in the rain, which is likely to accelerate the aging, failure, and shedding of the coating, thereby reducing the sun protection effect. Especially some low-quality parasols are easily damaged in the event of heavy rain because the sunscreen coating is not properly treated. At the same time, studies have shown that when the umbrella surface is wet, due to the optical transmission of water, the transmittance of ultraviolet rays may increase, which leads to a decrease in the sun protection effect.
3. The higher the UPF value, the better the sun protection ability of the parasol?
True appraisal: This statement has some truth, but it is not comprehensive enough.
UPF (Ultraviolet Protection Factor) refers to the ratio of the average effect of ultraviolet radiation calculated when the skin is unprotected to the average effect of ultraviolet radiation calculated when the skin is protected by fabric. It can be seen from this definition that the higher the UPF value, the better the UV protection effect.
As an important index to evaluate the UV protection function, UPF has been widely used in sunscreen umbrellas. However, the UPF cannot be used to assess the sun protection ability of umbrellas alone. According to the national standard GB/T 18830-2009 "Evaluation of Textile Anti-ultraviolet Performance", only when UPF is greater than 40 and T (UVA) AV (refers to UVA, the average transmittance of ultraviolet rays with a wavelength of 320 ~ 420 nm , The smaller the value, the smaller the transmittance) When it is less than 5%, it can be called "UV protection product". In other words, in addition to the UPF value, the T (UVA) AV value is also very important.
It should be pointed out that in the national standard, the highest mark of textile UPF value is 50+, that is, UPF>50. This is because when the UPF is greater than 50, the impact on the human body is negligible, so some products are marked with a very high UPF value (such as hundreds of thousands), and their actual sun protection effect is compared with the sun umbrella with UPF>50. There is no significant difference.
4. Is a black umbrella better than a white umbrella for sun protection?
True appraisal: Under the same conditions, the darker the umbrella surface, the lower the UV transmittance, and the better the UV protection performance.
The anti-ultraviolet ability of sunshades is affected by many factors, including fabric structure, tightness, thickness, color, fiber type, and anti-ultraviolet finishing. Therefore, when discussing the UV resistance of the umbrella surface, various factors should be considered comprehensively, rather than just looking at the color.
Under the same other conditions, the darker the color of the textile, the lower the UV transmittance, and the better the UV protection performance. At this time, the black umbrella is indeed more sun-proof than the white umbrella. This is mainly due to the selective absorption of light due to the difference in structure and performance of different dyes. Conjugated systems that are abundant in black dyes (the dyes containing conjugated systems have stronger ability to absorb ultraviolet rays) while selectively absorbing visible radiation, it also extends the absorption band to the ultraviolet region, which plays a role in absorbing ultraviolet rays. , Thereby reducing the transmittance of ultraviolet rays and improving the ultraviolet protection performance of the fabric.